Audi G28: 10 Things I'd Like To Have Known Earlier
How to Replace an Audi G28 Engine Speed Sensor
Charles the Humble Technician teaches you how to replace the G28 Engine Speed Sensor. This sensor is located on the edge of the transmission, above the flywheel ring gear. It transmits a signal to the ECU via a grey wire T55/49, then to the tachometer in the instrument cluster.
1. Engine Speed Sensor
The grey wire is situated at the edges of the transmission, above the flywheel ring. The sensor transmits signals through the grey wire to pin T55/49. The ECU utilizes this information to control boost and fuel. It also sends an indication to the G5 Tachometer within the instrument cluster.
The sensor serves as a reference point to connect with the G40 Camshaft Position Sensor. The ecu must be aware of when the crankshaft has reached TDC and also the position of the camshaft, to trigger the spark and injectors.
If this sensor fails the ECU will show the P00160 error, which means the Crank Shaft and Intake Camshaft are out of sync and possibly indicating the chain stretching or a jump link on the upper chain of timing. However, the error code won't appear on its own, without additional information from other sensors (G4 and G40).
It is a little tricky to test since there are several pins on the connector, and each one has different functions. The most effective method to test it is by measuring the resistance between the ECU and the sensor. If the sensor is operational, it should read around 1000 ohms. If you're having issues with this component, look for evidence of oil or coolant in the connector bay.
2. Injectors
Yesterday, while accelerating from the highway paytoll at maximum speed, i noticed a huge decrease in power. It was like the engine had run out of gas. Or my injectors weren't firing. I took out the spark plugs this morning, 3 were soaked in gasoline, and the fourth was dry. When I crank the engine, there are no sparks, i place a tissue on top of each injector hole, the 3 drenched with gazoline leap out, however the 4th stays closed. I inspected the ground connection on ECU pins 14/55, 30/55 and 48/55. i get 0ohm. I'm assuming that the issue is in another location.
I also tried to reset PID but without success. The car will start when the G28 is unplugged, and it works fine when the G28 plugged in. However the intermittent misfire issue persists at higher RPM. The coolant temperature sensor (G62) shows the wrong temp value -49c, even if I unplug it. I also noticed that the oil gauge in the cockpit shows 2 bars but the actual pressure is 0.
I'm not sure what to do. I think I've all other possibilities out. I'm concerned that i may have missed something. If anyone has any suggestions, please chime in! TIA!
3. Fuel Pump
The fuel pump in the g28 gets a signal from the RPM sensor. The GM-style transmitter is similar to the G4 sender and both work on the 80,100,200, UrS, and RS2 vehicles. It is easy to find an extra in a wrecking shop or a parts store. It is easy to test them - simply switch your DMM into resistance mode and measure the distance between pins 1 and 2 (with the bump at the connector's end facing upwards). They should be infinite Ohms.
4. ECU
The ECU in our 20vt turbo (3B AAN ABY) engines needs to know both the position and speed the crankshaft to make decisions regarding timing of the fuel injector, etc. audi key replacement uses a Crank Position Sensor G4 and an Engine Speed Sensor G28 to accomplish this. If you are experiencing issues with either of these sensors, the diagnostic scanner will show the codes that could trigger an engine shut down.
Some of the signs of a failing G28 sensor include an inaccurate gearbox rev counter the gears are shifting faster than normal and/or misfiring when in gear. If you have any of these issues, it is likely your sensor is going bad and should be replaced. They're inexpensive and easy to locate especially in the case of a Bosch model like ours. Alternately, GM's version this part would be an option.
5. Tachometer
A failing engine speed sensor could be a cause for a slew of issues in your car. It is an important part of the transmission in your Audi because it relays information to the ECU on how fast or slowly the car's engine is turning. This sensor can cause the transmission to malfunction and other components of the car to be affected.
The G5 engine speed sensor is located at the edge of the transmission above the flywheel ring gear. It sends a signal directly to the ECU at pin T55/49, via a grey wire. The ECU utilizes this signal to control the flow of fuel and boost as well as timig. It also relays it to the G5 Tachometer in instrument cluster. You can test the sensor for failure by checking continuity between it and the tachometer. You can also check continuity between ECU pin T55/49 and the instrument cluster connection on pin T6a/1 (trace [79trace [79]) and between T6a/1 and the instrument cluster pin T26a/12. There should be an average resistance of 1000 ohms between these two points. This is a common part that is found across the Audi 80, 100 200, UrS and RS2 range from 1985 MC through the 1997 UrS AAN and 1995 RS2 ADU so good ones might be availble in wrecking yards.